Recent years have seen rapid advances in the technology of converting image information to electric signals, transmitting and/or storing the signals and/or regenerating the same on a cathode ray tube (CRT). Along with these advances, increasingly high levels of requirements have been set forth for hard copies reproduced from such image information, and various hard copy producing means have been proposed. However, most of the means proposed heretofore give only hard copies of inferior image quality which are not as good as prints obtained by using currently available color papers. A typical process capable of providing hard copies with high image quality is "FUJI PHOTO FILM'S PICTOGRAPHY".TM., which uses a silver halide thermal development dye diffusion system and an LED scanning exposure system. However, this process is still unsatisfactory from the viewpoints of photosensitive material cost and process stability.
On the other hand, improvements in silver halide photosensitive materials and development of compact, simple and rapid development systems (e.g. minilaboratory system) have made it possible to provide printed photographs having very high quality in a relatively simple manner, in a short time period and at low cost. Therefore, hard copy materials which are inexpensive and can give hard copies of high image quality rapidly and always stably manifesting their performance characteristics as well as an image-forming method adapted to such materials are keenly demanded.
For obtaining hard copies from electric signals, the so-called scanning exposure system is generally used in which image information data are drawn out in succession for exposure as is disclosed in EP 0,350,046. Photosensitive materials suited for use in such system are therefore required. For obtaining hard copies rapidly using silver halide photosensitive materials, it is necessary to shorten both the time required for this scanning exposure and the time required for development. For shortening this scanning exposure time, it is necessary to use a light source with high output power so that the exposure time per picture element can be as short as possible. However, it is well known that higher illuminance, and shorter time exposure of silver halide emulsion grains results in weak development activity of latent images formed upon exposure, leading to a slower rate of development and to a greater change in photographic characteristics due to changes in processing bath composition. Furthermore, when an attempt is made to shorten the development time, the changes in photographic characteristics due to changes in processing bath composition tend to be much more increased. Accordingly, a technology is required by which latent images formed by high illuminance, and short time exposure can be developed in the shortest possible time and in a stable manner.
So far, glow lamps, xenon lamps, mercury-vapor lamps, tungsten lamps and light-emitting diodes, among others, have been used as light sources for exposure in recording devices or instruments which use the scanning exposure system. However, these light sources are disadvantageous from the practical viewpoint in that they are weak in output power and short in life. For avoiding these disadvantages, scanners are available which use coherent laser light sources, such as He-Ne lasers, argon lasers, He-Cd lasers, other gas lasers, and semiconductor lasers, as light sources for scanning exposure.
Gas lasers are high in output power but have drawbacks: they are large-sized and expensive and require modulators. On the other hand, semiconductor lasers are not only small-sized and inexpensive but also advantageous in that their emissions can be easily modulated and they have a longer life than gas lasers. Semiconductor lasers are therefore best suited for use in a system for obtaining hard copies rapidly and at low cost. This type of system is the general technical field of the present invention.
However, the wavelength of light emitted by these semiconductor lasers is in most cases in the infrared region. Therefore, photosensitive materials showing high photosensitivity in the infrared region which assure rapid and stable development following high illuminance scanning exposure, as well as an image forming method adapted to such materials, becomes necessary. However, the conventional infrared-sensitive photosensitive materials are inferior, in the stability of latent images after exposure, to photosensitive materials spectrally sensitized in the visible region, and such infrared-sensitive materials are subject to greater changes in photographic characteristics upon changes in the development process. In the case of high illuminance laser exposure, the photographic changes in such processes are further intensified. Thus, it has been impossible to put scanning exposure using such lasers to practical use.
Meanwhile, European Patent EP-0277589 discloses a color photosensitive material in which a class of compounds reactive with an aromatic amine compound are used for inhibiting staining which occurs during storage of color photographs due to the aromatic amine compound remaining in the photographs after development. When such compounds are used in photosensitive materials for ordinary printer exposure (about 1/10 to several seconds), the undesirable fluctuation in photographic characteristics due to changes in developer composition is accentuated. Improvements are therefore required.